RenaSci

Diabetic Complications

Kidney Histology

 

Our rodent models of type 2 diabetes (eg STZ-treated mice and rats on high fat diet; diabetic ZDF rats and db/db mice) are being developed to investigate the effects of drugs on serious microvascular complications of diabetes such as diabetic nephropathy and diabetic neuropathy. 


Diabetic Nephropathy


Diabetes is one of the leading causes of kidney disease and 10-20% of patients with diabetes die of renal failure. Diabetic nephropathy develops slowly over time and appears to be due to progressive damage to nephrons in the kidney caused by high blood glucose levels.


Markers of renal impairment and diabetic nephropathy include:

 

     •     Increased urinary albumin

     •     Increased urinary total protein

     •     Increased TIM-1 and cystatin-C in urine (clinical markers of renal damage) 

     •     Hyperfiltration (increased glomerular filtration rate) 

     •     Kidney hypertrophy (increased kidney weight)

     •     Histopathological changes eg glomerular sclerosis and interstitial fibrosis

 

We have a number of metabolic cages which can be used for collection of urine throughout studies in mice or rats. Biomarkers of renal damage can be measured using conventional assays and kits or our Cobas c 111 clinical chemistry analyser.

Plasma creatinine and blood urea nitrogen (BUN) levels can also be measured if required. 

The effects of drugs on glomerular filtration rate in rats and mice can be assessed using the FITC inulin clearance test.

At termination, kidneys can be removed and kidney sections can be weighed (to measure kidney hypertrophy) and prepared for histopathological examination eg Periodic Acid Schiff (PAS) staining can be used to demonstrate increased glomerular sclerosis and Azan Trichrome staining can be used to assess collagen levels and demonstrate interstitial fibrosis.


STZ/ High Fat Diet Model of Diabetic Nephropathy

Following treatment with STZ, rats and mice maintained on high fat diet develop diabetes and clear signs of the development of diabetic nephropathy.

Kidney Histology in STZ-treated Mice on High Fat Diet

 

The STZ/high fat diet model of diabetic nephropathy has been validated using the angiotensin receptor antagonist, losartan, and a novel dual inhibitor of neutral endopeptidase and endothelin converting enzymes (see Reiche et al. 2011).

 

ZDF Rat Model of Diabetic Nephropathy 

 

RenaSci have recently investigated the development of diabetic nephropathy in ZDF rats displaying severe diabetes. Male ZDF rats with the genotype fa/fa  (ZDF) were compared to control animals with the phenotype +/+ or +/fa. The results demonstrate that these animals develop impaired renal function and can be used as a model of diabetic nephropathy.

Increased Urinary Albumin and Total Protein in ZDF Rats

Increased Levels of Markers of Renal Damage in Urine of ZDF Rats

Increased Glomerular Filtration Rate in ZDF Rats

Histological Evidence of Diabetic Nephropathy in ZDF Rats

 

We have also recently established the adriamycin-induced nephropathy mouse model of chronic kidney disease. This model complements our exisitng models of diabetic nephropathy but has the advantage that it is of short duration as it does not depend on the development or progression of diabetes.

 

Diabetic Neuropathy


Diabetic peripheral neuropathy is a common chronic complication of diabetes. Symptoms often include the progressive loss of thermal and tactile pain sensation. This form of diabetic neuropathy occurs mainly in the nerves in the feet and legs. Damage to the feet often occurs and if undetected can result in severe infection leading to amputation. In some patients, however, diabetic peripheral neuropathy can produce painful symptoms.

Diabetic neuropathy can be assessed in animal models of diabetes by measuring :-

     •     Thermal pain sensitivity (Hargreaves test). This test measures the latency
            of an animal to withdraw a hind paw from a radiant heat source

     •     Mechanical allodynia (von Frey test). This test determines the threshold at
           which an animal will withdraw a hind paw from mechanical pressure applied
           from calibrated von Frey filaments

We have shown the development of thermal hypoalgesia and mechanical allodynia in STZ-treated rodents maintained on a high fat diet.

Thermal Hypoalgesia in STZ-treated Mice on High Fat Diet

Mechanical Allodynia in STZ-treated Rats on High Fat Diet

 

The reduction in mechanical withdrawal threshold produced by a single administration of STZ in rats on a high fat diet can be prevented by chronic administration of the antidiabetic agents, metformin and linagliptin.

 

Metformin and Linagliptin Prevent Mechanical Allodynia in STZ-treated Rats on High Fat Diet 

Figure taken from Byrne et al. 2015. Please click here to see the full paper.

 

Please contact us for further information on our rat and mouse models of diabetic nephropathy and diabetic neuropathy.

 

Posters

 

Byrne et al. 2012. Characterisation of the high fat diet/streptozotocin model of diabetes and the effects of the PPARɤ ligand pioglitazone. Abstract No. PF232. 14th World Congress on Pain, International Association for the Study of Pain, Milan, Italy. 27th-31st August 2012.

 

Cheetham et al. 2015. Markers of diabetic nephropathy in the ZDF rat model of diabetes. Abstract No. 572-P. American Diabetes Association 75th Scientific Sessions, Boston, Massachusetts, USA, 5th-9th June 2015.

 

Reiche et al. 2011. Chronic administration of a new dual NEP/ECE inhibitor or lorsartan improves renal function in mice with diabetic nephropathy. Abstract No. 1011-P. American Diabetes Association 71st Scientific Sessions, San Diego, California, USA, 24th-28th June 2011.

 

Manuscripts

 

Byrne et al. 2015. Characterisation of pain responses in the high fat diet/streptozotocin model of diabetes and the analgesic effects of antidiabetic treatments. J Diabetes Res 2015. Available online: doi: 10.1155/2015/752481. [PubMed]